Definition of "involuntary" [in•vol•un•ta•ry]

• Acting or done without or against one's will: an involuntary participant in what turned out to be an argument. (adjective)
• Not subject to control of the volition: gave an involuntary start. See Synonyms at spontaneous. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• ""I'd never heard of the term 'involuntary resignation,' " said Committeeman Mike DeBlasi, who recalled "several occurrences" in the past year in which the quality of the school's Human Resources Department's work was called into question."
• "Gaskell has used the term involuntary nervous system."
• "[Sidenote: 1111a] Again, we do not usually apply the term involuntary when a man is ignorant of his own true interest; because ignorance which affects moral choice constitutes depravity but not involuntariness: nor does any ignorance of principle (because for this men are blamed) but ignorance in particular details, wherein consists the action and wherewith it is concerned, for in these there is both compassion and allowance, because he who acts in ignorance of any of them acts in a proper sense involuntarily."